The impractical part is really about carrying that much fuel. The problem is you to speed up and then slow down at the other end. Slowing down takes fuel (obvio

The impractical part is really about carrying that much fuel. The problem is you to speed up and then slow down at the other end. Slowing down takes fuel (obviously) but you have tos peed up that fuel at the beginning as it increases the overall payload. That's what I mean by impractical. New Horizons launched on an Atlas V 551. Falcon Heavy has a larger payload capacity so it might be more possible. But if you're relying on an engine to decelerate more than gravity then that creates another problem: whgat engine do you use? Remember it has to probably survive in space for possibly 10+ years and fire successfully. The Apollo lander used a super-simple engine for this reason, so much so that it could only ever be fired once (to launch back into Moon orbit) so it couldn't even be test-fired [1]. So what you'd put on a deep space probe is a significant unsolved problem. [1]: https://space.stackexchange.com/questions/36226/why-could-the-lunar-ascent-engine-be-used-only-once https://space.stackexchange.com/questions/36226/why-could-th...